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busdvr
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4 Posts
Discussion Starter · #1 ·
I recently upgraded to a 10 speed shimano setup and I am experiencing chainrub on the large chainring and the second-most largest cog on the cassette. I have a Performance's microshift shifters, DA 7800 fd, a 50-36 r700 crankset, an ultegra 6700 chain and a 12-23 10 speed rear cassette. I'm running into what I would consider unacceptable chainrub on the inside of the front derailleur cage when running in the 50-21 combo. I've setup the fd as per park tool's website and alignment, h/l set screws limits look okay. Any suggestions on eliminating the chainrub? or is this a normal occurrence?
 

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Los Barriles, BCS, Mexico
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1,454 Posts
Chain rub can be a function of chainstay length; shorter chainstays can equal rub to varying degrees. Secondarily, you may have too much tension on your derailleur cable. Slacken your cable just a bit and re-do your low limit screw. Conventional wisdom says don't crosschain.
 

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Rub it............
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3,833 Posts
Are you using the "trim" feature of the front shifter?

After shifting into the big ring, push the smaller button just one time. I will let a little bit of slack out and allow the front derailleur to move approx 1-2mm. This is trim.
 

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21,544 Posts
Nope

DaveT said:
Slacken your cable just a bit and re-do your low limit screw. Conventional wisdom says don't crosschain.
There is absolutely no reason that the low limit screw could be involved in any way when the chain is on the big ring. Also, the big ring to second largest cassette cog is not generally considered to be crosschained.
 

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busdvr
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4 Posts
Discussion Starter · #6 ·
I give the trim feature on the small shift lever another try. Initially, any force placed on the smaller shift lever dropped me down to the 36 chainring. Thanks, good gouge though.
 

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'brifter' is f'ing stupid
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DaveT said:
Secondarily, you may have too much tension on your derailleur cable. Slacken your cable just a bit and re-do your low limit screw. Conventional wisdom says don't crosschain.
i never understand advice like this...read the OP's post again and rethink your reply.
 

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Rub it............
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billk said:
I give the trim feature on the small shift lever another try. Initially, any force placed on the smaller shift lever dropped me down to the 36 chainring. Thanks, good gouge though.

No gouge at all. Quite a few riders do not know about the trim feature on the front shifter. But since you have tried the trim, try giving a little bit of slack back into the cable tension. I've found out with the Micro-shift shifters, tension needs to be perfect for the trim feature.
 

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Los Barriles, BCS, Mexico
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1,454 Posts
Kerry Irons said:
There is absolutely no reason that the low limit screw could be involved in any way when the chain is on the big ring. Also, the big ring to second largest cassette cog is not generally considered to be crosschained.

cxwrench said:
i never understand advice like this...read the OP's post again and rethink your reply.
Both of you are absolutely correct! My feeble dyslexic brain fixated on the rear derailleur, not the front. Sorry guys.

The OP's problem does sound like it may be too much tension of the front der cable though.
 
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